The present invention relates to image sensors and methods of manufacturing the same, and, more particularly, to image sensors that include photo-electric converting units for detecting different wavelengths of light.
An image sensor converts an optical image into an electrical signal. In recent years, with the development of the computer industry and the communication industry, an image sensor that has an improved function has been increasingly demanded for various devices, such as digital cameras, camcorders, PCSs (Personal Communication Systems), game devices, CCTV cameras, medical micro-cameras, and robots.
Some image sensors include color filters to reproduce colors of optical images. In image sensors that include color filters, when Bayer color filters are used, four unit pixels form one pixel group. In this case, the four unit pixels include two unit pixels that correspond to green, and two unit pixels that correspond to red and blue, respectively. That is, neighboring unit pixels are divided into red, green, and blue unit pixels that accumulate charges corresponding to the amount of incident light having wavelengths in the red, green, and blue regions, respectively. Each unit pixel includes a photoelectric-converting unit that accumulates charges corresponding to the amount of incident light.
When the wavelength of incident light is long, the incident light will penetrate more deeply into the semiconductor substrate. The wavelength of red light is longer than the wavelength of green light, which is in turn longer than the wavelength of blue light. Accordingly, in the red unit pixel, the incident light penetrates more deeply into the semiconductor substrate, but in the blue unit pixel, the incident light does not penetrate as deeply into the semiconductor substrate. For this reason, photoelectric-converting units that are provided in all of the unit pixels are formed deeply to collect all of the incident light. However, when impurities that form the photoelectric-converting units are implanted deeply into the semiconductor substrate, it is likely that the impurities will diffuse into adjacent regions. Accordingly, if the photoelectric-converting units are formed to be deep, lower regions of neighboring photoelectric-converting units may be easily connected due to diffusion, and, thus, a phenomenon known as “blooming” may more easily occur.
Alternatively, in order to collect incident light of different wavelengths, the photoelectric-converting units of the unit pixels can be formed to have different depths according to the wavelength of light detected by the pixel. However, in order to form the photoelectric-converting units of all the unit pixels to have different depths, it may be necessary to perform a photomask process at least three times, which can result in lower productivity and/or increased development/manufacturing costs.